Two strains of chickens which have undergone genetic selection for hyperuricemia (HUA strain) or hypouricemia (LUA strain) differ markedly in renal clearance of uric acid. They differ in uptake of uric acid by kidney slices and in the levels of K and Na needed for initiation of and/or maximal uptake of uric acid. Dietary Na, K and Cl concentrations were found to influence plasma uric acid concentrations in the LUA but not the HUA strain. Studies in this laboratory will focus on two aspects of uric acid transport: 1) The effect of Na, K and Cl on renal secretion of uric acid and 2) isolation, purification and kinetic assay of uric acid binding factor(s) in low speed pellet (950 times g) of kidney homogenate. The Sperber technique will be used to measure changes in renal uric acid secretion in response to monovalent ions administered to chickens intravenously or supplied in the diet. Variations in composition of urine and plasma will be monitored to determine the role of acid-base balance in urate secretion. Uric acid binding activity has been extracted (using Triton X-100) from the heavy particulate fraction of kidney. The binding factor(s) will be purified and the kinetics of uric acid binding determined. The role of binding factor in hyperuricemia and gout will be investigated.